Mantle convection modeling on parallel virtual machines

Thermally driven convection within the earth's mantle determines one of the longest time scales of our planet. Plate tectonics, the piecewise continuous movement of the earth's surface, is the prime manifestation of this slow deformational process but ultimately all large scale geological activity and dynamics of the planet involves the release of potential energy in the mantle. Massively parallel supercomputers are now allowing us to construct models of mantle convection with unprecedented complexity and realism. Here we present results from an approach to parallel computation that relies on explicit message-passing and distributed computing. Connecting workstations together as a single parallel machine over a network and using the parallel virtual machine software (PVM), we are able to perform computations in the hundreds of Mflops range with a demonstrated total parallel overhead of less than ten percent. We have run high resolution thermal convection calculations for the earth's mantle on the Los Alamos 16-node cluster of IBM RS/6000 workstations employing a finite element mesh with more than 1.3 million grid points. These results indicate this approach to parallel computing offers a practical and efficient means of utilizing a broad spectrum of parallel hardware.